Coeliac Disease in 2016: a shared care between GPs and Gastroenterologists

Posted September 5, 2016

By Dr Roslyn Vongsuvanh

Coeliac disease is an autoimmune mediated disorder of the small bowel, precipitated by gluten exposure in genetically predisposed individuals¹. It is characterised by an inappropriate immune response to dietary gluten with chronic inflammation and damage of the small bowel mucosa leading to bowel symptoms and nutrient deficiencies. Although classically thought of as a disease affecting younger individuals of European descent, coeliac disease is increasingly found in populations in North Africa, India, China and the Middle East²and the most common age for diagnosis is between 30 and 45. Coeliac disease is a common disorder in Australia, affecting one in 70 individuals, however, it is estimated that 80 per cent remain undiagnosed³. Coeliac disease can present with classical, overt symptoms but most patients present with atypical or subclinical disease. Primary care physicians have a critical role in recognising the diverse manifestations of coeliac disease and improving rates of diagnosis.

What symptoms in my patient should make me consider coeliac disease as a diagnosis?

The clinical manifestations of CD can be classic, atypical or subclinical. Classic symptoms are more common in infants and young children and include diarrhea or steatorrhoea, flatulence, abdominal distension and weight loss. In the majority of adults, the presentation of coeliac disease is subtler with only mild non-specific gastrointestinal complaints. In a meta-analysis with 3,383 subjects with coeliac disease, the prevalence of irritable bowel syndrome-type symptoms was 38 per cent⁴. These symptoms included erratic bowel habits, constipation, chronic abdominal pain and bloating. Some patients have subclinical disease with non-specific symptoms such as fatigue; have nutrient deficiencies (most commonly of iron) or are asymptomatic. Given the range of manifestations, the index of suspicion for coeliac disease required by the clinician is high. The 2015 NICE guidelines on coeliac disease provide recommendations on when to offer testing and when to consider testing for coeliac disease in individuals⁵. These are summarised in Table 1.

Table 1: NICE 2015 Guidelines on when to test for coeliac disease

Offer testing to patients with any of the following:	Consider testing in patients with any of following:
Persistant unexplained abdominal or gastrointestinal symptoms Faltering growth Prolonged fatigue Unexpected weight loss Severe or persistent mouth ulcers Unexplained iron, vitamin B12 or folate deficiency Type 1 diabetes, at diagnosis Autoimmune thyroid disease, at diagnosis Irritable bowel syndrom (in adults) First-degree relatives of people with coeliac disease	Metabolic bone disorder (reduced bone mineral density or osteomalacia) Unexplained neurological symptoms (particularly peripheral neuropathy of ataxia) Unexplained subfertility or recurrent miscarriage Persistently raised liver enzymes with unknown cause Dental enamel defects Down’s syndrome Turner syndrome

How do I test for coeliac disease?

Serology is usually the first step in screening for coeliac disease. The following steps are recommended:

Is my patient currently on a gluten free diet? If no, proceed with serological testing. If yes, the patient must undergo a gluten challenge to avoid a false negative result. A gluten challenge consists of eating at least two slices of wheat-containing bread per day for at least four weeks⁶.
The following tests should be ordered:

a. First choice: IgA anti-tissue transglutaminase (TTG) and total IgA

b. Use IgA endomysial antibodies (EMA) if IgA tTG is weakly positive (IgA endoysial antibodies are highly specific but less sensitive than TTG antibodies)

c. If IgA deficient, consider IgG based tests – IgG antiendomysial, IgG anti-gliadin, IgG-TTG

d. Note: most Australian laboratories will include the following tests when “coeliac serology” is requested:

i.Anti-gliadin (IgA and IgG)

ii. Anti-TTG (IgA and IgG)

How do I interpret coeliac serology?

Positive serology

If a patient’s screening serological tests are positive, they need to be referred to a gastroenterologist for gastroscopy and confirmatory small bowel biopsies. Serology alone is insufficient to make a diagnosis of coeliac disease.

Negative serology

Consider the following reasons for potential false negative coeliac serology:

IgA deficiency – affects two to three per cent of patients who have coeliac disease
Gluten free diet – serology can be negative after being on gluten free diet for more than three months
Children two years of age

It is important to recognise that two to three per cent of patients with coeliac disease have negative serology, have low antibody levels or have levels that fluctuate between positive and negative¹. Therefore, if coeliac serology is negative but the clinical suspicion of coeliac disease is high, the patient should be referred to a gastroenterologist for definitive histological testing.

The role of genetic testing

HLA-DQ2/8 genetic testing is useful in specific circumstances. HLA-DQ2 and or 8 are found in almost all patients with coeliac disease. However, it is also found in almost 50 per cent of the general population but only three per cent of these patients will develop coeliac disease1. Therefore, the main utility of HLA-DQ2/8 testing is to rule out coeliac disease: ie given that 99 per cent of patients with coeliac disease carry one of these markers, a negative test effectively rules out coeliac disease. A positive test is less useful and cannot be used for diagnosis⁷.

When do I refer to a gastroenterologist?

Refer to a gastroenterologist in the following situations:

A patient with positive coeliac serology for confirmatory small bowel biopsies
A patient with negative coeliac serology but high index of suspicion of coeliac disease

Gastroscopy and histology

A gastroscopy with small bowel biopsies is the only definitive way to confirm the diagnosis of coeliac disease. Patients must be on gluten to avoid false negative results. Macroscopically, the duodenal folds may appear flattened with scalloping or fissuring. On histology, the most characteristic features of coeliac disease include blunted or atrophic villi, increased intraepithelial lymphocytes (IELs) and crypt hyperplasia1. Increased IELs in isolation is a common finding and most patients with this do not have coeliac disease. Increased IELs without structural change can be due to giardiasis, helicobacter pylori infection, crohn’s disease and common variable immune deficiency¹.

Management of coeliac disease

Gluten-free diet

A strict gluten-free diet (GFD) lifelong is currently the only therapy for coeliac disease. All people with coeliac disease require a strict GFD, regardless of the severity of their symptoms. Initial referral to a dietitian with special interest in coeliac disease is highly recommended by local and international guidelines. A GFD reduces symptoms, improves morbidity, improves nutritional parameters and reduces the risk of long-term complications of coeliac disease including osteoporosis and lymphoma. Clinical symptoms usually abate within the first few weeks of commencing a strict GFD.

A GFD implies that all wheat, barley and rye products must be avoided. Coeliac Australia³, recommends different groups of food that are suitable for those on a GFD. Naturally gluten-free foods includes fresh fruits and vegetables, legumes, milk, eggs, nuts and gluten-free grains such as rice and corn. Products labeled ‘gluten-free’ or have the ‘Coeliac Australia’ endorsement logo, also do not have gluten. It is important to avoid cross-contamination by avoiding products which ‘may contain gluten’. It is important to ensure the patient has adequate fibre and B-group vitamins, as these are derived from gluten-containing grains⁷. Patients are encouraged to join Coeliac Australia for excellent resources and links.

Monitoring of coeliac disease

After initial diagnosis, the general physician has a critical role in monitoring for disease activity and assessing for complications of coeliac disease. At six months in the first year following diagnosis and annually thereafter, the following should be assessed:

Coeliac serology
FBC
Folic acid, iron, B12, zinc
Thyroid function
Calcium, phosphate, vitamin D
Liver function tests

A DEXA scan should also be organised within the first year following diagnosis. The gastroenterologist will usually organise a repeat gastroscopy and small bowel biopsies after 12 months to assess for persistent histological damage.

Non-dietary therapy and future directions

Non-dietary therapy such as corticosteroids and immune modulators, are restricted largely to refractory coeliac disease (1-2% of coeliac disease patients). Studies are underway on agents that prevent T cell activation, however only 2 at present are in phase 2 clinical trials¹.

References

Kelly CP, Bai JC, Liu E, Leffler Advances in diagnosis and management of celiac disease. Gastroenterology. 2015 May;148(6):1175-86.
Schuppan D, Dieterich Pathogenesis, epidemiology, and clinical manifestations of celiac disease in adults. UpToDate. 2015
Coeliac Australia: Diagnosing Coeliac Disease- the key facts. http://www.coeliac.org.au
Sainsbury A, Sanders DS, Ford AC. Prevalence of irritable bowel syndrome-type symptoms in patients with celiac disease: a meta-analysis. Clin Gastroenterol Hepatol 2013; 11:359.
NICE (UK) guidelines: Coeliac disease: recognition, assessment and management (2015). nice.org.uk/guidance/ng20
Ludvigsson JF, Bai JC, Biagi F, et al. Diagnosis and management of adult coeliac disease: guidelines from the British Society of Gut 2014;63:1210–28.
Kenrick K and Day Coeliac Disease: where are we in 2014? Australian Family Physician 2015; 43:674-678